Molding conduits



Ulla. IG

Sept.21 1926. l T. E. MURRAY MOLDING CONDUITS original Filed July 17 1925 Patented' sept. 21, 1926.

UNITED STATES 1,600,696 PATENT OFFICE.

THOMAS E. MURRAY, 0F BROQKLYlN', NEW YORK.;

MOLDING CONDUITS.

Application filed July 17, 1925, Seria1No. 44,195. Renewed March 2, 1926.

The invention is particularly applicable to the laying or buildinf of concrete structures formed with ducts, generally a few inches in diameter, for electric cables. It is also applicable to other plastic materials than concrete and to the forming of structures with openings of various sizes and shapes.

The accompanying drawings illustrate an' embodiment of the invention.

yliig. 1 is a perspective view; A Ilfig. 2 is a longitudinal section of a detai Fig. 3 is a longitudinal section, partly in elevation, of a portion of the apparatus in use; I

Fig. 4 is a cross-section near the rear end of the apparatus.

The invention is shown in connection with an apparatus similar to that described in previous applications, for example, my application No. 754,471 and in my Patent No. 1,525,087 of February 3, 1925. In these apparatus the concrete conduit is laid in placel and by a sort of extrusion process the apparatus is moved ahead of the conduit progressively as the latter is shaped and rammed to compact it.

The apparatus comprises a pair of side' plates 1 which are connected at intervals in their length by cross-braces 2 and 3 in which are Xed steel tubes 4 within which are carried tubes 5 made of high grade rubber with thick walls so as to withstand the blows and pressures of the concrete without substantial distortion and to be so elastic that they can'by pulling them lengthwise be contracted transversely sufficiently to free them from the surrounding concrete and to permit their withdrawal, all as described more fully in a certain prior application No. 67 O,- 423., A ram 6 extends across the rear portion of the ,space between the plates land has sleeves 7 freely sliding on the ends of the tubes 4. The ram is connected by links 8 to side arms 9 which are pivoted at their lower ends to the sides of the apparatus as indicated at 10 and which are connected at their upper ends to an operating handle 11. When the handle is pushed forward (to the left) a space is left beyond the forward end of .the completed portion of the conduit, which space is occupied only bythe cores 5. The concrete is cast about these cores. The ram is then pushed to the rear. This operation compacts the concrete and `at the same time causes the entire apparatus crete immediately at the rear of the ram; the

rubber cores being carried through and well beyond the rear ends of the steel tubes so as to furnish asupport for the walls of the ducts as the apparatus, with the steel tubes, was advanced. This, however, meant the making of the ducts first of the external diameter of the steel tubes andthe subse- `uent settling of the concrete to bring the iarneter of the ducts to that of the external diameter of the rubber cores. With the present apparatus I avoid this difficulty by hav.' ing the concrete molded in the first place directly on the rubber cores.

Fig. 3 illustrates this. The concrete 12 is cast between the lates 1 and against the face of the ram 6 directly around the cores 5. The latter are moved forward, either in short steps with each movement of the operating lever 11 or at longer intervals as may be desired, in the latter case giving more timefor the concrete to set before withdrawingthe cores. They must, of course, be of such length and the ap aratus must be advanced at such a rate t at they will not be withdrawn from the duct until the concrete ha-s set suiiiciently'to hold its shape. The

ram 6 is provided with openings through which the cores 5 pass with a fairly close fit. The sleeves 7 surrounding the ends of the tubes 4 are of suilicient length to permit the desired limited movement of the ram with respect tol such tubes. Thusthe tubes 4 serve their purpose of providing a long bearing which will hold the cores. 5 in proper line and position and of providing guides for the reciprocation of the ram 6.

Various modifications of the apparatus illustrated may be made by those skilled in the art without departure from the invention as defined in the following claims.

What I claim` is: 1. An apparatus for molding conduits comprising a rubber core of sutlicient strength to support the external pressures of the molded material, a. ram for compact-v ing the material longitudinally about said' core and a tube'for holdjnghand guiding said core located forward of t e ram' so as not to project into the space in which the concrete is cast.

2J The apparatus of claim 1, said guiding and supporting tube arrangedvto act 1Q comprising a rubber core o v sufficient for ho-ldin signed my name.

strength to support the external pressures of the molded material, aI ram for compacting the 'material about said core and means forward o the ram so as not' toU roject into the space. in which theA concrete 1s cast.` In witness whereof, I have hpreunto THOMAS E. MURRAY,

and guiding saidcore located 

